Add plugdev group for FIDO2 device access.

The u2f udev rules set GROUP=plugdev on hidraw devices, but the
group didn't exist. Create it and add kyle to it so FIDO2 keys
are accessible without relying on logind uaccess ACLs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

configuration.nix

@@ -75,6 +75,7 @@
   services.cron.enable = true;
 
   programs.zsh.enable = true;
+  users.groups.plugdev = {};
   users.mutableUsers = true;
   users.users.kyle = {
     initialPassword = "password";
@@ -88,6 +89,7 @@
       "disk"
       "kvm"
       "networkmanager"
+      "plugdev"
       "video"
     ];
     shell = pkgs.zsh;